| Topic: |
Religions > Atheism |
| User: |
"Michael Gray" |
| Date: |
19 Nov 2007 03:17:37 PM |
| Object: |
OT: Ozanges? |
Origins of Citrus Are Here
(Australasian Science, Vol 28, No 10)
"Australia's contribution to global cuisine may be more than just the
macadamia nut and the kangaroo steak.It seems the citrus family may
have evolved here rather than in South-East Asia.
"There are about 25 true species of citrus, and some 50% of these are
from Papua New Guinea, New Caledonia and Australia, while most
commercial species and cultivars such as mandarins, oranges and lemons
originated in Asia," says Prof David Mabberley, Director of the
Botanic Gardens in Washington and an adjunct professor at the
University of Western Sydney (UWS).
The idea that Australia and New Guinea are the original source of the
citrus family evolved out of attempts by UWS entomologist Prof Andrew
Beattie to protect Australia's citrus crops against the disease
huanglongbing, which is also known as citrus greening.
"When dealing with the vector and disease we would find a host plant
with foul' different names in the literature," Beattie says.
"The scientific naming of citrus plants is a disaster."
Beattie went to see Mabberley about the confusion arising from
multiple names for citrus plants, and found he had already
demonstrated that some Australasian species previously placed in
another genus belonged as citrus plants.
When looking at the species Mabberley had designated it struck Beattie
that the Australian varieties seemed more morphologically primitive.
This led the pair to consider the possible origins for the genus and
how equatorial currents could have allowed the buoyant fruit to float
from one continent to another.
They concluded that citrus originated in this part of the world,
either as an Australasian or a Gondwanan native.
"Papers on molecular biology suggest the genus is less than 71 million
years old, so it began after the break-up of eastern Gondwana,"
Beattie adds.
The origins of tile genus are more than a matter for national pride.
Beattie says that in preparing to fight invasive species such as
huanglongbing it is crucial to know how species are related to each
other so that we can predict which species are vulnerable to
infection.
Already the citrus greening bacterium has been found in parts of Papua
New Guinea, and Beattie is concerned that rare species may be wiped
out if it travels any further, particularly to nearby New Ireland.
He hopes a better understanding of the citrus genealogy will spur
conservation efforts. "
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